import shapefile
import utm

r = shapefile.Reader("shapefiles/footprints/footprints_se")
w = shapefile.Writer("shapefiles/footprints/footprints_185")
w.fields = list(r.fields)
for sr in r.shapeRecords():
    utmPoints = []
    for p in sr.shape.points:
        x, y, band, zone = utm.from_latlon(p[1], p[0])
        utmPoints.append([x, y])
    area = abs(shapefile.signed_area(utmPoints))  # 绝对值
    if area <= 100:
        w.record(*sr.record)
        w.shape(sr.shape)
r.close()
w.close()

r = shapefile.Reader("shapefiles/footprints/footprints_185")
print(r)
r.close()